The present invention is directed to a replacement pivot pin for a joint of an articulated system having at least a pair of arms that swing or rotate relative to each other wherein a sensor utilizing the Hall effect provides information to a remote location as to the angular position of one arm relative to the other.
Articulated arms are utilized on many types of equipment including construction equipment such as backhoes, excavators, mechanical arms such as on undersea exploration vehicles and on space vehicles such as the space station. Most of such arms can be visualized by an operator who controls the arms from a master controller which may be very closely spaced relative to the arm or at a substantial distance in which case the arm may be viewed by video. When the user can see the position of the arms relative to each other and to their environment, the operator uses such visual information to control the relative position of the arms.
However, in certain circumstances the operator cannot visually see the arms or the arm is to be controlled by a computer. In such a situation it is necessary for the operator or computer to be able to determine the relative position of the arms by some other method. Furthermore, even if the arms can be seen, it is sometimes helpful or important for the information to be transmitted elsewhere for use in conjunction with computer programs, for data storage or the like.
As most articulated arm systems are not initially provided with some type of position sensor, it is also important that such a device be easily retrofitted to articulated systems. Some sensory devices also require substantial modification of the equipment or addition of parts such as shafts that extend outwardly and add complexity to the equipment and that may make the equipment subject to breakdown.
Some types of position sensing devices utilize contacts that are located about an articulating joint. However, contact sensors are not a very viable solution for equipment that must operate under conditions that can foul the contacts or wear on the contacts. Contact sensors may also not have the sensitivity required for many uses of such a device. Many types of position sensors can not function in severe or hazardous service.
It is also noted that some types of position sensors are placed in hydraulic cylinders that move the arms. Such sensors present problems because the leads must pass through a high pressure barrier and many hydraulic systems are converting from an oil to a water based system. While the oil does not cause conductivity problems, the water can short out such systems.
Therefore, a position sensor that does not require major modification is desirable for use in determining relative positions of arms in an articulated device wherein the positions can be transmitted to remote locations and wherein the sensor can withstand rugged conditions and is highly sensitive to small changes in position.